In addition to
shore height zonation, there was distinct variation in type and range of habitat preferences. Of the
5 study islands, Quirimba and Quisiva had the greatest intertidal habitat variety end the largest number
of resident hermit crab species. The number of hermit crab species peaked at 10 in the lower-shore
zone and decreased upshore to 3 supra-littoral species and downshore to 8 subtldal species. In contrast.
the density of hermit crab Individualsp eaked in the upper mid-shore, at 3 m ' The mid-shore zone was
also the primary reglon of cluster formation, principally involving Clibanarius laevimanus and Cllbanarius
vlrescens, although 3 other species were also involved. The activity of the 2 semi-terrestrial
species, Coenoblta rugosus and Coenobita cavlpes, on Quirimba lsland was principally related to the
1ight:dark cycle but was strnkinglyd ifferent between open and mangrove habitats. Sornc degree of
activity took place in both specles throughout a 24 h period in the mangrove habitat, where the peak of
feedlng activlty was twice that of the open sand-scrub habitat. Wind strength was a major influence on
the activity of C. rugosus and C. cavipes, reducing the number of active indviduals to zero at higher
wlnd speeds, even in thinly mangroved habitats.